sgillmore...Don't move the tank over the CG with the Magnum engine unless you add pump. One benefit of the YS engines is they have a pump already. If you add a pump fine, if not then leave the tank forward. Many have left the tank in it's stock position and state it flys fine there. I think you are correct you will have to move the rudder servo to the tail. I did that on mine. Not that hard really. I really love this plane. It flys wild and nice all at the same time.
Thanks
Barry